1. Field of the Invention
The invention relates to compositions effective as feeding stimulants/aggregants for subterranean termites and for masking the presence of other chemicals to subterranean termites.
2. Description of the Prior Art
Damage in the United States attributable to subterranean termites is now estimated to be in excess of one billion dollars a year. All wooden or wood-containing structures are potentially affected, including homes, outbuildings, fences, utility poles, railway sleepers, boats, bridges, retaining walls and even living trees. Of perhaps even greater concern, the Formosan subterranean termite, Coptotermes formosanus, has become one of the most destructive pests in the contiguous United States since its introduction to this country within the last half-century. Reasons for this include their massive colonies which can contain tens of millions of individuals, their ability to attack several species of living trees, and their high level of reproduction.
The most successful existing methods for control of subterranean termites are preventive rather than remedial. These include barrier treatments to structures and the preemptive treatment of wood materials with chemicals to prevent termite attack. These however have drawbacks. Physical barriers are not compatible for retrofitting on many existing constructions and may not be completely effective, and chemical treatments are only partially effective and last only about five years.
Baits have been increasingly utilized for monitoring and/or controlling subterranean termites. Typical commercially available baits include a cellulose containing material as a food source, provided within a termite accessible housing or container. These bait stations are placed beneath the soil in an area where termites are suspected, and periodically monitored for evidence of termite feeding or infestation. Upon indication of termites, the cellulose containing material may be replaced with a new bait containing a cellulose containing material in combination with a termiticide such as a slow-acting toxicant or termite growth regulator.
Using baits to deliver a termiticide has several advantages. Baits typically require only a small amount of the termiticide, and they target only the termites that feed on the bait. Thus non-target organisms are not affected. Moreover, the use of a bait often makes it unnecessary to locate the nest. Because many termites, including the Formosan termite, C. formosanus, distribute food to other termites in the colony, the termiticide laced food may be spread throughout a colony after feeding by only a few foraging termites. Baits utilizing low toxicity termiticides in this manner have shown success in reducing damage caused by subterranean termites. Baits containing diflubenzuron and hexaflumuron have been particularly effective in suppressing large colonies of C. formosanus. 
However, conventional baits suffer from several disadvantages. Subterranean termites may typically find their food by random probing. Consequently, without anything to attract the termites, the bait stations are often bypassed and left uneaten. Moreover, many termiticide or other compounds incorporated into baits are repellant to the termites, limiting the use of such agents. The present state of the art is limited to the use of a few non-repellant termiticides and low concentrations, less than 100 ppm, of some effective but moderately repellant termiticides. This increases both the time and the amount of bait which must be consumed by the termites for the termite colony to attain lethal levels of the active compound. It also increases the likelihood that the termites may learn to avoid feeding on the bait before such levels are attained.
While various methodologies and compositions have been developed, there remains a need for improved methods and compositions for monitoring and controlling termites.